1. Field of the Invention
The present invention relates to an engine model carburetor, and more particularly to, an engine model carburetor capable of adjusting oil automatically when decelerating.
2. Description of the Prior Art
FIG. 1 is a partial sectional view of a conventional model engine. FIG. 2 is a sectional view of a conventional model engine carburetor. The model engine comprises a cylinder 1. The cylinder 1 comprises a piston 2 therein. The cylinder 1 is further connected with a carburetor 3. The carburetor 3 has an air passage 4 therein, and a first connection hole 5 and a second connection hole 6 to communicate with the air passage 4. A middle-speed oil needle 7 is provided in the first connection hole 5. A throttle 8 is provided in the second connection hole 6. An oil supply valve 9 is provided at an outer side of the carburetor 3. The oil supply valve 9 communicates with the middle-speed oil needle 7. Fuel oil is first poured in the oil supply valve 9, and then flows to the middle-speed oil needle 7. When the user starts the model engine, the negative pressure generated by the piston 2 will draw the external air to enter the cylinder 1 through the air passage 4 of the carburetor 3. Because the passage C defined between the middle-speed oil speed 7 and the throttle 8 is smaller than the air passage 4, the air passing the passage C will accelerate to form negative pressure. Through the Bernoulli principle, the fuel oil in the middle-speed oil needle 7 is drawn to the air passage 4 to mix with the air to form oil gas. Then, the oil gas enters the cylinder 1 for ignition to push the piston 2 to reciprocate.
Referring to FIG. 1 and FIG. 2, the user controls the distance between the middle-speed oil needle 7 and the throttle 8 to change the size of the passage C so as to control the air flow entering the air passage 4 to adjust the rotation speed of the piston 2. For example, the throttle 8 is moved away from the middle-speed oil needle 7 to enlarge the passage C so as to increase the air flow entering the air passage 4, such that the rotation speed of the piston 2 is increased. However, the running of the model engine is not in sequence. Sometimes, the speed is decelerated at a very short time from a high speed. It is named oil-return. At this time, the throttle 8 will slide toward the middle-speed oil needle 7 quickly to reduce the passage C quickly, so that the air flow entering the air passage 4 will be decreased greatly. The fuel oil ratios of the oil gas is too high, namely, the oil gas is too thick. When this kind of oil gas enters the cylinder 1, the model engine will not run smoothly to accumulate carbon in the cylinder 1 and to waste the fuel oil. The model engine may extinguish. Accordingly, the inventor of the present invention has devoted himself based on his many years of practical experiences to solve these problems.